nutrition (C3) Flashcards
Tooth type ( incisors, canines, pre molars and molars) functions
Incisors: biting and cutting
Canines: tearing and ripping meat
pre molars and molars: grinding and chewing
Teeth functions
mechanical digestion
increase SA for enzyme action
Herbivore diet and adaptations
- cellulose based ( difficult to digest )
- teeth adapted for GRINDING to increase SA for bacterial cellulase enzyme action
Herbivore structural dentition features
HORNY PAD: grass wraps around tongue pulling across hp on upper jaw
INCISORS: slice through plant material
DIASTEMA: middle gap for large grinding surface
MOLARS: interlocking M and W for grinding
LOOSE ARTICULATION: side to side circular grinding action
Carnivore dentition features
SMALL SHARP INCISORS: grip and tear flesh from bone
LARGE CURVED CANIES: seize and hold prey
PRE/MOLARS: cutting and crushing food
CARNASSIALS: slide like blades and crush bone
POWERFUL VERTICAL JAW: open wide without dislocation and grip prey
Ruminant herbivore examples and diet
cows, goats and sheep
much cellulose yet unable to digest as lack of enzyme cellulase, they have a four chambered stomach
Ruminant adaptations
Rely on mutalistic (rumin) bacterium living in gut which secrete cellulase enzymes, live in stomach chamber rumen - glucose fermentation occurs, digest cellulose to beta glucose
Ruminant cellulose digestion
- grass chewed, mixed with saliva, swallowed
- passes into RUMEN, churned, mixed with bacteria secreting cellulase. b glucose absorbed in blood for energy
- undigested grass passes to RETICULUM to form CUD that’s regurgitated to mouth for more chewing
- cud passes to OMASUM where waters absorbed into blood
- in ABOMASUM (true stomach) bacteria are killed and digested proving source of PROTEIN for animal
Non ruminant herbivore example
rabbits
Non ruminant adaptations (2)
CAECUM enlarged accommodating cellulose digestion bacteria
REFECTION occurs where rabbit ingests faecal pellets so material passes gut twice increasing digestion efficency
Types of nutrition and sub categories
autotrophic ( photoautotrophic and chemoautotrophic)
heterotrophic ( holozoic, saprotrophic, parasitic )
Autotrophic nutrition definition
organisms that synthesisze their own complex organic molecules from simpler molecules using either light (photo) or chemical (chemo) energy
Photoautotrophic definition and examples
organisms use energy for sunlight to carry out photosynthesis to make organic molecules ( glucose) from inorganic, c02 and water
e.g green plants, algae, some bacteria
Chemoautotrophic definition and examples
organisms using energy from chemical reactions to synthesize organic molecules
e.g bacteria respiring in DEEP sea HYDROTHERMAL VENTS
Heterotrophic nutrition definition and types
organisms ( consumers ) cannot produce own organic molecules and so consume complex organic molecules from other organisms, break this material down to smaller soluble molecules which then absorb and assimilate
- holozoic
- saprotrophic
- parasitic
Holozoic definition and examples
organisms INGEST food, DIGEST it, ABSORB into bloodstream, ASSIMILATE and EGEST indigestible remains - INTRACELLULAR digestion
e.g mostly animals, also some protoctista such as amoeba
includes:
CARNIVORNS ( flesh eating )
HERBIVORES ( plant eating )
OMNIVORES ( ‘all eaters’ significant in natural diet)
DETRITIVORES ( decomposing, dead or fecal organic matter )
Holozoic unicellular organism example
AMEOBA - obtains nutrients such as oxygen and glucose through cell MEMBRANE, take in large food molecules via ENDOCYTOSIS and indigestible remains egested by EXOCYTOSIS, digestion is intacellular
Holozoic simple multicellular organisms example
HYDRA - undifferentiated digestive system, prey is digested, absorbed and indigestible remains egested through same mouth (single opening digestive system)
Saprotrophic nutrition definition and example
feed on dead or decaying organic material and carry out extracellular digestion, enzymes are secreted onto food material outside body, then absorb soluble products of digestion via diffusion or active transport
e.g fungi, some bacteria
Parasitic nutrition definition and examples
organisms that live on (ectoparasite) or in (endoparasite) another organism (host) and obtain nourishment at the expense of the host therefore often causing harm or death of host
e.g pork tapeworm, headlice
What is the structure and the functions of the mammalian gut wall? number of layers?
- 5 layers; lumen mucosa, sub-mucosa, muscularis (inner-circular, outer-longitudinal), serosa
- thickness of layers varies in different regions of gut
- MUCOSA - lines the gut wall, INNER most layer with epithelium, EPITHELIUM secrets MUCUS, lubricating and protecting mucosa (some regions secretes digestive juices others is absorbs digested food)
- SUB-MUCOSA - connective tissue containing BLOOD and LYMPH VESSELS removing products of digestion, contains NERVES coordinating peristalsis
- MUSCULARIS - inner-circular and outer-longitudinal; coordinated waves of contraction (PERISTALSIS), pushing the BOLUS along alimentary canal
- SEROSA - OUTERMOST layer, TOUGH connective tissue PROTECTING gut wall, reduces FRICTION with other abdominal organs during peristalsis
What are the regions of the digestive system (mouth to anus) and functions? x10
BUCCAL CAVITY - ingestion; mechanical digestion of food; crushing and chewing action of teeth, tongue assists chewing of food into bolus, chemical digestion of starch by salivary amylase secreted by salivary glands
OESOPHAGUS - carriage of food to stomach via peristalsis
STOMACH - mechanical digestion; contraction of muscles to churn food, secretion of hydrochloric acid, chemical digestion; of proteins by enzymes i.e. pepsin
LIVER - secretes bile via the gall bladder and bile duct which helps break down lipids/fats
DUODENUM - first section of small intestine; receives pancreatic juices from pancreas, bile from gall bladder, chemical digestion of carbohydrates, lipids and proteins
ILEUM - second section of small intestine; chemical digestion of carbohydrates, lipids and proteins, absorption of digested food
CAECUM - first section of large intestine; connects small intestine to colon
COLON - large intestine; absorption of water, mineral ions, vitamins
RECTUM - final region of L.I. storage of faeces
ANUS - site of egestion
What are the roles of saliva and mucus in digestion?
SILIVA - watery secretion containing:
• AMYLASE; hydrolysing STARCH —–> MALTOSE
• BICARBONATE IONS creating an optimum ph for amylase enzyme (ph 7.8 - slightly alkaline)
• MUCUS which lubricates the food and gut wall
What are the stages involved in starch digestion?
- CHEMICAL digestion of starch and glycogen begins in the BUCCAL cavity where salivary glands secrete SALIVARY AMYLASE (starch -> maltose)
- starch digestion stops in the stomach due to the acidic conditions
- digestion continues in the DUODENUM where pancreas secretes PANCREATIC AMYLASE via pancreatic DUCT (starch -> maltose)
- MALTOSE is hydrolysed further by MALTASE (on epithelial cell membranes) to ALPHA-GLUCOSE in the ileum
What are the stages in digestion of lactose and sucrose?
chemical digestion of:
LACTOSE to glucose and galactose by LACTASE SUCROSE to glucose and fructose by SUCRASE
Where are sites of production for carbohydrase’s, gut regions where they function and usual pH levels?
site of production and regions:
• buccal cavity (salivary glands)
• pancreas (pancreatic glands)
• epithelial cells of small intestine/duodenum, ileum
ph. levels;
• 7.8
What are the stages in digestion of proteins?
proteases:
- ENDOPEPTIDASE - hydrolyse (NON-TERMINAL) peptide bonds WITHIN the protein molecule and form peptides from polypeptide proteins
e. g PEPSIN - STOMACH (ph2), optimal in acidic conditions, secreted by GASTRIC glands in stomach mucosa, secreted as INACTIVE PEPSINOGEN which is activated by HCl forming pepsin
e. g TRYPSIN - DUODENUM (ph7/8), pancreatic secretion entering duodenum via pancreatic duct, duodenum secretes ENTEROKINASE to convert the pancreas secretion of inactive trypsinogen to trypsin - EXOPEPTIDASE - hydrolyse the TERMINAL bonds of the short peptides, from the free AMINO END end or the free CARBOXYL end, forming amino acids
What is the role of bile? ph? made? stored? works? contains?
BILE is made in the LIVER, stored in the GALL BLADDER and passed through the bile DUCT into the DUODENUM
• bile is ALKALINE and NEUTRALISES ACID in food from stomach creating optimum ph. for enzyme action on small intestine (ph7.8)
• bile contains BILE SALTS (hydrophilic outer side and hydrophobic inner side)
• EMULSIFY lipid globules in partially digested food, large GLOBULES are broken down into SMALLER EMULSIFIED DROPLETS - increasing surface area for lipase action
What is the role of pancreatic lipase? secreted from to where?
pancreatic lipase secreted into in the duodenum of small intestine:
hydrolysis of triglycerides to fatty acids and glycerol
Where is final digestion and absorption of amino acids, glucose, fatty acids and glycerol?
- digestion on the MEMBRANES of EPITHELIAL cells covering the VILLI
- absorption of AMINO ACIDS by ACTIVE transport into the EPITHELIAL cells and FACILITATED diffusion into the CAPILLARIES
- absorption of GLUCOSE and other monosaccharides into epithelial cells by CO-TRANSPORT (with sodium ions) and then into capillaries by FACILITATED diffusion
- GLUCOSE and AMINO ACIDS are transported via the HEPATIC PORTAL VEIN to the LIVER
• FATTY ACIDS and GLYCEROL DIFFUSE into the epithelial cells, where they are reassembled into TRIGLYCERIDES - then pass into the LACTEAL and are carried via the lymphatic system to the blood
